Incompatible Changes and Limitations in Apache Impala (incubating)

The Impala version covered by this documentation library contains the following incompatible changes. These
are things such as file format changes, removed features, or changes to implementation, default
configuration, dependencies, or prerequisites that could cause issues during or after an Impala upgrade.

Even added SQL statements or clauses can produce incompatibilities, if you have databases, tables, or columns
whose names conflict with the new keywords. See
Impala Reserved Words for the set of reserved words for the current
release, and the quoting techniques to avoid name conflicts.

Incompatible Changes Introduced in Impala 2.9.x

For the full list of issues closed in this release, including any that introduce
behavior changes or incompatibilities, see the
changelog for Impala 2.9.

Incompatible Changes Introduced in Impala 2.8.x

Llama support is removed completely from Impala. Related flags (--enable_rm)
and query options (such as V_CPU_CORES) remain but do not have any effect.

If --enable_rm is passed to Impala, a warning is printed to the log on startup.

The syntax related to Kudu tables includes a number of new reserved words,
such as COMPRESSION, DEFAULT, and ENCODING, that
might conflict with names of existing tables, columns, or other identifiers from older Impala versions.
See Impala Reserved Words for the full list of reserved words.

The DDL syntax for Kudu tables, particularly in the CREATE TABLE statement, is different
from the special impala_next fork that was previously used for accessing Kudu tables
from Impala:

The DISTRIBUTE BY clause is now PARTITIONED BY.

The INTO N BUCKETS
clause is now PARTITIONS N.

The SPLIT ROWS clause is replaced by different syntax for specifying
the ranges covered by each partition.

The DESCRIBE output for Kudu tables includes several extra columns.

Non-primary-key columns can contain NULL values by default. The
SHOW CREATE TABLE output for these columns displays the NULL
attribute. There was a period during early experimental versions of Impala + Kudu where
non-primary-key columns had the NOT NULL attribute by default.

The IGNORE keyword that was present in early experimental versions of Impala + Kudu
is no longer present. The behavior of the IGNORE keyword is now the default:
DML statements continue with warnings, instead of failing with errors, if they encounter conditions
such as "primary key already exists" for an INSERT statement or
"primary key already deleted" for a DELETE statement.

The replication factor for Kudu tables must be an odd number.

A UDF compiled into an LLVM IR bitcode module (.bc) might
encounter a runtime error when native code generation is turned off by
setting the query option DISABLE_CODEGEN=1.
This issue also applies when running a built-in or native UDF with
more than 20 arguments.
See IMPALA-4432 for details.
As a workaround, either turn native code generation back on with the query option
DISABLE_CODEGEN=0, or use the regular UDF compilation path
that does not produce an IR module.

Incompatible Changes Introduced in Impala 2.7.x

Bug fixes related to parsing of floating-point values (IMPALA-1731 and IMPALA-3868) can change
the results of casting strings that represent invalid floating-point values.
For example, formerly a string value beginning or ending with inf,
such as 1.23inf or infinite, now are converted to NULL
when interpreted as a floating-point value.
Formerly, they were interpreted as the special "infinity" value when converting from string to floating-point.
Similarly, now only the string NaN (case-sensitive) is interpreted as the special "not a number"
value. String values containing multiple dots, such as 3..141 or 3.1.4.1,
are now interpreted as NULL rather than being converted to valid floating-point values.

Incompatible Changes Introduced in Impala 2.6.x

The default for the RUNTIME_FILTER_MODE
query option is changed to GLOBAL (the highest setting).

The RUNTIME_BLOOM_FILTER_SIZE setting is now only used
as a fallback if statistics are not available; otherwise, Impala
uses the statistics to estimate the appropriate size to use for each filter.

Admission control and dynamic resource pools are enabled by default.
When upgrading from an earlier release, you must turn on these settings yourself
if they are not already enabled.
See Admission Control and Query Queuing for details
about admission control.

Impala reserves some new keywords, in preparation for support for Kudu syntax:
buckets, delete, distribute,
hash, ignore, split, and update.

For Kerberized clusters, the Catalog service now uses
the Kerberos principal instead of the operating sytem user that runs
the catalogd daemon.
This eliminates the requirement to configure a hadoop.user.group.static.mapping.overrides
setting to put the OS user into the Sentry administrative group, on clusters where the principal
and the OS user name for this user are different.

The mechanism for interpreting DECIMAL literals is
improved, no longer going through an intermediate conversion step
to DOUBLE:

Casting a DECIMAL value to TIMESTAMPDOUBLE produces a more precise
value for the TIMESTAMP than formerly.

Certain function calls involving DECIMAL literals
now succeed, when formerly they failed due to lack of a function
signature with a DOUBLE argument.

Improved type accuracy for CASE return values.
If all WHEN clauses of the CASE
expression are of CHAR type, the final result
is also CHAR instead of being converted to
STRING.

The initial release of Impala 2.5 sometimes has a higher peak memory usage than in previous releases
while reading Parquet files.
The following query options might help to reduce memory consumption in the Parquet scanner:

Reduce the number of scanner threads, for example: set num_scanner_threads=30

The S3_SKIP_INSERT_STAGING query option, which is enabled by
default, increases the speed of INSERT operations for S3 tables.
The speedup applies to regular INSERT, but not INSERT OVERWRITE.
The tradeoff is the possibility of inconsistent output files left behind if a
node fails during INSERT execution.
See S3_SKIP_INSERT_STAGING Query Option (Impala 2.6 or higher only) for details.

Certain features are turned off by default, to avoid regressions or unexpected
behavior following an upgrade. Consider turning on these features after suitable testing:

Impala now recognizes the auth_to_local setting,
specified through the HDFS configuration setting
hadoop.security.auth_to_local.
This feature is disabled by default; to enable it,
specify --load_auth_to_local_rules=true
in the impalad configuration settings.

A new query option, PARQUET_ANNOTATE_STRINGS_UTF8,
makes Impala include the UTF-8 annotation
metadata for STRING, CHAR,
and VARCHAR columns in Parquet files created
by INSERT or CREATE TABLE AS SELECT
statements.

A new query option,
PARQUET_FALLBACK_SCHEMA_RESOLUTION,
lets Impala locate columns within Parquet files based on
column name rather than ordinal position.
This enhancement improves interoperability with applications
that write Parquet files with a different order or subset of
columns than are used in the Impala table.

Incompatible Changes Introduced in Impala 2.5.x

The admission control default limit for concurrent queries (the max requests
setting) is now unlimited instead of 200.

Multiplying a mixture of DECIMAL and FLOAT or
DOUBLE values now returns
DOUBLE rather than DECIMAL. This
change avoids some cases where an intermediate value would underflow or overflow
and become NULL unexpectedly. The results of
multiplying DECIMAL and FLOAT or
DOUBLE might now be slightly less precise than
before. Previously, the intermediate types and thus the final result
depended on the exact order of the values of different types being
multiplied, which made the final result values difficult to
reason about.

Previously, the _ and % wildcard
characters for the LIKE operator would not match
characters on the second or subsequent lines of multi-line string values. The fix for issue
IMPALA-2204 causes
the wildcard matching to apply to the entire string for values
containing embedded \n characters. This could cause
different results than in previous Impala releases for identical
queries on identical data.

Formerly, all Impala UDFs and UDAs required running the
CREATE FUNCTION statements to
re-create them after each catalogd restart.
In Impala 2.5 and higher, functions written in C++ are persisted across
restarts, and the requirement to
re-create functions only applies to functions written in Java. Adapt any
function-reloading logic that you have added to your Impala environment.

CREATE TABLE LIKE no longer inherits HDFS caching settings from the source table.

The SHOW DATABASES statement now returns two columns rather than one.
The second column includes the associated comment string, if any, for each database.
Adjust any application code that examines the list of databases and assumes the
result set contains only a single column.

The output of the SHOW FUNCTIONS statement includes
two new columns, showing the kind of the function (for example,
BUILTIN) and whether or not the function persists
across catalog server restarts. For example, the SHOW
FUNCTIONS output for the
_impala_builtins database starts with:

Incompatible Changes Introduced in Impala 2.4.x

Other than support for DSSD storage, the Impala feature set for Impala 2.4 is the same as for Impala 2.3.
Therefore, there are no incompatible changes for Impala introduced in Impala 2.4.

Incompatible Changes Introduced in Impala 2.3.x

Note:

The use of the Llama component for integrated resource management within YARN
is no longer supported with Impala 2.3 and higher.
The Llama support code is removed entirely in Impala 2.8 and higher.

For clusters running Impala alongside
other data management components, you define static service pools to define the resources
available to Impala and other components. Then within the area allocated for Impala,
you can create dynamic service pools, each with its own settings for the Impala admission control feature.

If Impala encounters a Parquet file that is invalid because of an incorrect magic number,
the query skips the file. This change is caused by the fix for issue IMPALA-2130.
Previously, Impala would attempt to read the file despite the possibility that the file was corrupted.

Previously, calls to overloaded built-in functions could treat parameters as DOUBLE
or FLOAT when no overload had a signature that matched the exact argument types.
Now Impala prefers the function signature with DECIMAL parameters in this case.
This change avoids a possible loss of precision in function calls such as greatest(0, 99999.8888);
now both parameters are treated as DECIMAL rather than DOUBLE, avoiding
any loss of precision in the fractional value.
This could cause slightly different results than in previous Impala releases for certain function calls.

Formerly, adding or subtracting a large interval value to a TIMESTAMP could produce
a nonsensical result. Now when the result goes outside the range of TIMESTAMP values,
Impala returns NULL.

Formerly, it was possible to accidentally create a table with identical row and column delimiters.
This could happen unintentionally, when specifying one of the delimiters and using the
default value for the other. Now an attempt to use identical delimiters still succeeds,
but displays a warning message.

Formerly, Impala could include snippets of table data in log files by default, for example
when reporting conversion errors for data values. Now any such log messages are only produced
at higher logging levels that you would enable only during debugging.

Incompatible Changes Introduced in Impala 2.2.x

Changes to File Handling

Impala queries ignore files with extensions commonly used for temporary work files by Hadoop tools. Any
files with extensions .tmp or .copying are not considered part of the
Impala table. The suffix matching is case-insensitive, so for example Impala ignores both
.copying and .COPYING suffixes.

The log rotation feature in Impala 2.2.0 and higher
means that older log files are now removed by default.
The default is to preserve the latest 10 log files for each
severity level, for each Impala-related daemon. If you have
set up your own log rotation processes that expect older
files to be present, either adjust your procedures or
change the Impala -max_log_files setting.
See Rotating Impala Logs for details.

Changes to Prerequisites

The prerequisite for CPU architecture has been relaxed in Impala 2.2.0 and higher. From this release
onward, Impala works on CPUs that have the SSSE3 instruction set. The SSE4 instruction set is no longer
required. This relaxed requirement simplifies the upgrade planning from Impala 1.x releases, which also
worked on SSSE3-enabled processors.

Incompatible Changes Introduced in Impala 2.1.x

Changes to Prerequisites

Currently, Impala 2.1.x does not function on CPUs without the SSE4.1 instruction set. This minimum CPU
requirement is higher than in previous versions, which relied on the older SSSE3 instruction set. Check
the CPU level of the hosts in your cluster before upgrading to Impala 2.1.

Changes to Output Format

The "small query" optimization feature introduces some new information in the
EXPLAIN plan, which you might need to account for if you parse the text of the plan
output.

New Reserved Words

New SQL syntax introduces additional reserved words:
FOR, GRANT, REVOKE, ROLE, ROLES,
INCREMENTAL.
As always, see Impala Reserved Words
for the set of reserved words for the current release, and the quoting techniques to avoid name conflicts.

Incompatible Changes Introduced in Impala 2.0.5

No incompatible changes.

Incompatible Changes Introduced in Impala 2.0.4

No incompatible changes.

Incompatible Changes Introduced in Impala 2.0.3

Incompatible Changes Introduced in Impala 2.0.2

No incompatible changes.

Incompatible Changes Introduced in Impala 2.0.1

The INSERT statement has always left behind a hidden work directory inside the data
directory of the table. Formerly, this hidden work directory was named
.impala_insert_staging . In Impala 2.0.1 and later, this directory name is changed to
_impala_insert_staging . (While HDFS tools are expected to treat names beginning
either with underscore and dot as hidden, in practice names beginning with an underscore are more widely
supported.) If you have any scripts, cleanup jobs, and so on that rely on the name of this work directory,
adjust them to use the new name.

The abs() function now takes a broader range of numeric types as arguments, and the
return type is the same as the argument type.

Shorthand notation for character classes in regular expressions, such as \d for digit,
are now available again in regular expression operators and functions such as
regexp_extract() and regexp_replace(). Some other differences in
regular expression behavior remain between Impala 1.x and Impala 2.x releases. See
Incompatible Changes Introduced in Impala 2.0.0 for details.

Incompatible Changes Introduced in Impala 2.0.0

Changes to Prerequisites

Currently, Impala 2.0.x does not function on CPUs without the SSE4.1 instruction set. This minimum CPU
requirement is higher than in previous versions, which relied on the older SSSE3 instruction set. Check
the CPU level of the hosts in your cluster before upgrading to Impala 2.0.

Changes to Query Syntax

The new syntax where query hints are allowed in comments causes some changes in the way comments are
parsed in the impala-shell interpreter. Previously, you could end a
-- comment line with a semicolon and impala-shell would treat that
as a no-op statement. Now, a comment line ending with a semicolon is passed as an empty statement to
the Impala daemon, where it is flagged as an error.

Impala 2.0 and later uses a different support library for regular expression parsing than in earlier
Impala versions. Now, Impala uses the
Google RE2 library
rather than Boost for evaluating regular expressions. This implementation change causes some
differences in the allowed regular expression syntax, and in the way certain regex operators are
interpreted. The following are some of the major differences (not necessarily a complete list):

.*? notation for non-greedy matches is now supported, where it was not in earlier
Impala releases.

By default, ^ and $ now match only begin/end of buffer, not
begin/end of each line. This behavior can be overridden in the regex itself using the
m flag.

By default, . does not match newline. This behavior can be overridden in the regex
itself using the s flag.

\Z is not supported.

< and > for start of word and end of word are not
supported.

Lookahead and lookbehind are not supported.

Shorthand notation for character classes, such as \d for digit, is not recognized.
(This restriction is lifted in Impala 2.0.1, which restores the shorthand notation.)

Changes to Output Format

In Impala 2.0 and later, user() returns the full Kerberos principal string, such as
user@example.com, in a Kerberized environment.

The changed format for the user name in secure environments is also reflected where the user name is
displayed in the output of the PROFILE command.

In the output from SHOW FUNCTIONS, SHOW AGGREGATE FUNCTIONS, and
SHOW ANALYTIC FUNCTIONS, arguments and return types of arbitrary
DECIMAL scale and precision are represented as DECIMAL(*,*).
Formerly, these items were displayed as DECIMAL(-1,-1).

Changes to Query Options

Changes to Configuration Options

The meaning of the --idle_query_timeout configuration option is changed, to
accommodate the new QUERY_TIMEOUT_S query option. Rather than setting an absolute
timeout period that applies to all queries, it now sets a maximum timeout period, which can be adjusted
downward for individual queries by specifying a value for the QUERY_TIMEOUT_S query
option. In sessions where no QUERY_TIMEOUT_S query option is specified, the
--idle_query_timeout timeout period applies the same as in earlier versions.

The --strict_unicode option of impala-shell was removed. To avoid
problems with Unicode values in impala-shell, define the following locale setting
before running impala-shell:

export LC_CTYPE=en_US.UTF-8

New Reserved Words

Some new SQL syntax requires the addition of new reserved words: ANTI,
ANALYTIC, OVER, PRECEDING,
UNBOUNDED, FOLLOWING, CURRENT,
ROWS, RANGE, CHAR, VARCHAR.
As always, see Impala Reserved Words
for the set of reserved words for the current release, and the quoting techniques to avoid name conflicts.

Changes to Data Files

The default Parquet block size for Impala is changed from 1 GB to 256 MB. This change could have
implications for the sizes of Parquet files produced by INSERT and CREATE
TABLE AS SELECT statements.

Although older Impala releases typically produced files that were smaller than the old default size of
1 GB, now the file size matches more closely whatever value is specified for the
PARQUET_FILE_SIZE query option. Thus, if you use a non-default value for this setting,
the output files could be larger than before. They still might be somewhat smaller than the specified
value, because Impala makes conservative estimates about the space needed to represent each column as
it encodes the data.

When you do not specify an explicit value for the PARQUET_FILE_SIZE query option,
Impala tries to keep the file size within the 256 MB default size, but Impala might adjust the file
size to be somewhat larger if needed to accommodate the layout for wide tables, that is,
tables with hundreds or thousands of columns.

This change is unlikely to affect memory usage while writing Parquet files, because Impala does not
pre-allocate the memory needed to hold the entire Parquet block.

Incompatible Changes Introduced in Impala 1.4.4

No incompatible changes.

Incompatible Changes Introduced in Impala 1.4.3

No incompatible changes. The TLS/SSL security fix does not require any change in the way you interact with
Impala.

Incompatible Changes Introduced in Impala 1.4.2

None. Impala 1.4.2 is purely a bug-fix release. It does not include any incompatible changes.

Incompatible Changes Introduced in Impala 1.4.1

None. Impala 1.4.1 is purely a bug-fix release. It does not include any incompatible changes.

Incompatible Changes Introduced in Impala 1.4.0

There is a slight change to required security privileges in the Sentry framework. To create a new
object, now you need the ALL privilege on the parent object. For example, to create a
new table, view, or function requires having the ALL privilege on the database
containing the new object. See Enabling Sentry Authorization for Impala for a full list of operations and
associated privileges.

With the ability of ORDER BY queries to process unlimited amounts of data with no
LIMIT clause, the query options DEFAULT_ORDER_BY_LIMIT and
ABORT_ON_DEFAULT_LIMIT_EXCEEDED are now deprecated and have no effect.
See ORDER BY Clause for details about improvements to
the ORDER BY clause.

There are some changes to the list of reserved words. See
Impala Reserved Words for the most current list. The following
keywords are new:

API_VERSION

BINARY

CACHED

CLASS

PARTITIONS

PRODUCED

UNCACHED

The following were formerly reserved keywords, but are no longer reserved:

COUNT

GROUP_CONCAT

NDV

SUM

The fix for issue
IMPALA-973
changes the behavior of the INVALIDATE METADATA statement regarding nonexistent
tables. In Impala 1.4.0 and higher, the statement returns an error if the specified table is not in the
metastore database at all. It completes successfully if the specified table is in the metastore
database but not yet recognized by Impala, for example if the table was created through Hive. Formerly,
you could issue this statement for a completely nonexistent table, with no error.

Incompatible Changes Introduced in Impala 1.3.3

No incompatible changes. The TLS/SSL security fix does not require any change in the way you interact with
Impala.

Incompatible Changes Introduced in Impala 1.3.2

With the fix for IMPALA-1019, you can use HDFS caching for files that are accessed by Impala.

Incompatible Changes Introduced in Impala 1.3.1

In Impala 1.3.1 and higher, the REGEXP and RLIKE operators now match a
regular expression string that occurs anywhere inside the target string, the same as if the regular
expression was enclosed on each side by .*. See
REGEXP Operator for examples. Previously, these operators only
succeeded when the regular expression matched the entire target string. This change improves compatibility
with the regular expression support for popular database systems. There is no change to the behavior of the
regexp_extract() and regexp_replace() built-in functions.

The result set for the SHOW FUNCTIONS statement includes a new first column, with the
data type of the return value. See SHOW Statement for
examples.

Incompatible Changes Introduced in Impala 1.3.0

The EXPLAIN_LEVEL query option now accepts numeric options from 0 (most concise) to 3
(most verbose), rather than only 0 or 1. If you formerly used SET EXPLAIN_LEVEL=1 to
get detailed explain plans, switch to SET EXPLAIN_LEVEL=3. If you used the mnemonic
keyword (SET EXPLAIN_LEVEL=verbose), you do not need to change your code because now
level 3 corresponds to verbose. See
EXPLAIN_LEVEL Query Option for details about the allowed explain levels, and
Understanding Impala Query Performance - EXPLAIN Plans and Query Profiles for usage information.

The keyword DECIMAL is now a reserved word. If you have any databases, tables,
columns, or other objects already named DECIMAL, quote any references to them using
backticks (``) to avoid name conflicts with the keyword.

Note:
Although the DECIMAL keyword is a reserved word, currently Impala does not support
DECIMAL as a data type for columns.

The query option formerly named YARN_POOL is now named
REQUEST_POOL to reflect its broader use with the Impala admission control feature.
See REQUEST_POOL Query Option for information about the
option, and Admission Control and Query Queuing for details about its use with the
admission control feature.

There are some changes to the list of reserved words. See
Impala Reserved Words for the most current list.

The names of aggregate functions are no longer reserved words, so you can have databases, tables,
columns, or other objects named AVG, MIN, and so on without any
name conflicts.

The internal function names DISTINCTPC and DISTINCTPCSA are no
longer reserved words, although DISTINCT is still a reserved word.

The HDFS property dfs.client.file-block-storage-locations.timeout was renamed to
dfs.client.file-block-storage-locations.timeout.millis, to emphasize that the unit of
measure is milliseconds, not seconds. Impala requires a timeout of at least 10 seconds, making the
minimum value for this setting 10000. If you are not using cluster management software, you might need to
edit the hdfs-site.xml file in the Impala configuration directory for the new name
and minimum value.

Incompatible Changes Introduced in Impala 1.2.4

There are no incompatible changes introduced in Impala 1.2.4.

Previously, after creating a table in Hive, you had to issue the INVALIDATE METADATA
statement with no table name, a potentially expensive operation on clusters with many databases, tables,
and partitions. Starting in Impala 1.2.4, you can issue the statement INVALIDATE METADATA
table_name for a table newly created through Hive. Loading the metadata for
only this one table is faster and involves less network overhead. Therefore, you might revisit your setup
DDL scripts to add the table name to INVALIDATE METADATA statements, in cases where you
create and populate the tables through Hive before querying them through Impala.

Incompatible Changes Introduced in Impala 1.2.2

The following changes to SQL syntax and semantics in Impala 1.2.2 could require updates to your SQL code,
or schema objects such as tables or views:

With the addition of the CROSS JOIN keyword, you might need to rewrite any queries
that refer to a table named CROSS or use the name CROSS as a table
alias:

-- Formerly, 'cross' in this query was an alias for t1
-- and it was a normal join query.
-- In 1.2.2 and higher, CROSS JOIN is a keyword, so 'cross'
-- is not interpreted as a table alias, and the query
-- uses the special CROSS JOIN processing rather than a
-- regular join.
select * from t1 cross join t2...
-- Now if CROSS is used in other context such as a table or column name,
-- use backticks to escape it.
create table `cross` (x int);
select * from `cross`;

Formerly, a DROP DATABASE statement in Impala would not remove the top-level HDFS
directory for that database. The DROP DATABASE has been enhanced to remove that
directory. (You still need to drop all the tables inside the database first; this change only applies
to the top-level directory for the entire database.)

The keyword PARQUET is introduced as a synonym for PARQUETFILE in the
CREATE TABLE and ALTER TABLE statements, because that is the common
name for the file format. (As opposed to SequenceFile and RCFile where the "File" suffix is part of
the name.) Documentation examples have been changed to prefer the new shorter keyword. The
PARQUETFILE keyword is still available for backward compatibility with older Impala
versions.

New overloads are available for several operators and built-in functions, allowing you to insert their
result values into smaller numeric columns such as INT, SMALLINT,
TINYINT, and FLOAT without using a CAST() call. If you
remove the CAST() calls from INSERT statements, those statements might
not work with earlier versions of Impala.

Incompatible Changes Introduced in Impala 1.2.1

The following changes to SQL syntax and semantics in Impala 1.2.1 could require updates to your SQL code,
or schema objects such as tables or views:

In Impala 1.2.1 and higher, all NULL values come at the end of the result set for
ORDER BY ... ASC queries, and at the beginning of the result set for ORDER BY ...
DESC queries. In effect, NULL is considered greater than all other values for
sorting purposes. The original Impala behavior always put NULL values at the end, even for
ORDER BY ... DESC queries. The new behavior in Impala 1.2.1 makes Impala more compatible
with other popular database systems. In Impala 1.2.1 and higher, you can override or specify the sorting
behavior for NULL by adding the clause NULLS FIRST or NULLS
LAST at the end of the ORDER BY clause.

The new catalogd service might require changes to any user-written scripts that stop,
start, or restart Impala services, install or upgrade Impala packages, or issue REFRESH or
INVALIDATE METADATA statements:

The REFRESH and INVALIDATE METADATA statements are no longer needed
when the CREATE TABLE, INSERT, or other table-changing or
data-changing operation is performed through Impala. These statements are still needed if such
operations are done through Hive or by manipulating data files directly in HDFS, but in those cases the
statements only need to be issued on one Impala node rather than on all nodes. See
REFRESH Statement and
INVALIDATE METADATA Statement for the latest usage
information for those statements.

Incompatible Changes Introduced in Impala 1.2.0 (Beta)

There are no incompatible changes to SQL syntax in Impala 1.2.0 (beta).

The new catalogd service might require changes to any user-written scripts that stop,
start, or restart Impala services, install or upgrade Impala packages, or issue REFRESH or
INVALIDATE METADATA statements:

The REFRESH and INVALIDATE METADATA statements are no longer needed
when the CREATE TABLE, INSERT, or other table-changing or
data-changing operation is performed through Impala. These statements are still needed if such
operations are done through Hive or by manipulating data files directly in HDFS, but in those cases the
statements only need to be issued on one Impala node rather than on all nodes. See
REFRESH Statement and
INVALIDATE METADATA Statement for the latest usage
information for those statements.

The new resource management feature interacts with both YARN and Llama services.
See
Resource Management for Impala for usage information for Impala resource
management.

Incompatible Changes Introduced in Impala 1.1.1

There are no incompatible changes in Impala 1.1.1.

Previously, it was not possible to create Parquet data through Impala and reuse that table within Hive. Now
that Parquet support is available for Hive 10, reusing existing Impala Parquet data files in Hive requires
updating the table metadata. Use the following command if you are already running Impala 1.1.1:

ALTER TABLE table_name SET FILEFORMAT PARQUETFILE;

If you are running a level of Impala that is older than 1.1.1, do the metadata update through Hive:

Impala 1.1.1 and higher can reuse Parquet data files created by Hive, without any action required.

As usual, make sure to upgrade the Impala LZO package to the latest level at the same
time as you upgrade the Impala server.

Incompatible Change Introduced in Impala 1.1

The REFRESH statement now requires a table name; in Impala 1.0, the table name was
optional. This syntax change is part of the internal rework to make REFRESH a true
Impala SQL statement so that it can be called through the JDBC and ODBC APIs. REFRESH
now reloads the metadata immediately, rather than marking it for update the next time any affected
table is accessed. The previous behavior, where omitting the table name caused a refresh of the entire
Impala metadata catalog, is available through the new INVALIDATE METADATA statement.
INVALIDATE METADATA can be specified with a table name to affect a single table, or
without a table name to affect the entire metadata catalog; the relevant metadata is reloaded the next
time it is requested during the processing for a SQL statement. See
REFRESH Statement and
INVALIDATE METADATA Statement for the latest details about these
statements.

Incompatible Changes Introduced in Impala 1.0

If you use LZO-compressed text files, when you upgrade Impala to version 1.0, also update the
Impala LZO package to the latest level. See Using LZO-Compressed Text Files for
details.